We have continued the construction of a physical map contig of the 4p16.1 region in which we have previously established linkage for the Wolfram syndrome (DIDMOAD) and the Ellis van Creveld skeletal disorder. Mutation analysis was performed for the collapsin receptor gene and the MSX-1 homeobox gene in the above disorders respectively. In the continued effort to localize genes responsible for human disorder phenotypes we have localized genetic loci for Synpolydactyly type II, Brachydactyly type C and Parkinson's disease. Candidate genetic regions for a bipolar disorder susceptibility gene were also identified in a CEPH family. Similar genetic studies in spinocerebellar ataxia, essential tremor, and oculodentodigital syndrome are in progress.